Cocoa beans or seeds of the cocoa tree fruit have an inner portion or nib which is covered by a naturally affixed shell. After being harvested, raw cocoa beans may be fermented for a few days so that biochemical changes may take place which aid in developing flavor, reduce bitterness, and darken the seeds. The beans then are dried and polished (cleaned). The shells are cracked (e.g., mechanically, via intense infrared heat treatment, etc.), and then are removed and separated (“winnowed”) from the nibs. Typically, a small yet discernible portion of fractured nibs remain with the shell fraction after winnowing, as either attached to and/or loosely associated with the shell fragments. The cocoa beans may be preroasted before cracking and winnowing. Alternatively, the cocoa nibs may be separately roasted after winnowing. Roasting aids in developing flavor, aroma, and color in chocolate.
The cocoa nibs are a well-known source of cocoa butter and cake, and are processed in known manners to extract these and other nib components. The cocoa shells, however, also are a potentially valuable source of edible nutrients and dietary materials and contain cocoa nibs as the separation is not 100%. Cocoa shells contain, e.g., polyphenols (˜1-2%), alkaloids such as theobromine (˜1-2%), vitamins such as Vitamin D, minerals such as calcium and phosphorus, amino acids, as well as soluble and insoluble dietary fibers (˜25-30%), etc. The cocoa shells themselves also include approximately 6% shell fat, as well as the cocoa fat content and other compounds associated with any small portion of nibs still attached to and/or otherwise accompanying the shell fraction after winnowing. Roasted shells have also been used for aroma extraction. Cocoa shells have been used in flavored beverages, cocoa and chocolate production, mulch and fertilizer, and in ruminant livestock feed, etc. The cocoa shell portion of the cocoa beans may comprise approximately twelve to fifteen percent of the overall bean weight. Thus, aggregate amounts of the shells in high volume cocoa bean processing facilities can become substantial.
The cocoa shells, after separation from the nibs, have been converted into particulated forms to aid further handling, storage, and re-use of the shell material. Conventional mechanical milling of cocoa shells generally employs moving parts to effect attrition of the cocoa shells. Currently applied shell milling systems, include, e.g., beater blade mills, pin mills, differential mills, etc. Cocoa shells are extremely abrasive, which makes them difficult to mill and increases wear on equipment parts that contact them. As a result, mechanical milling of the shells is extremely costly in terms of machine maintenance. Mechanical milling also tends to generate localized heat and uncontrolled “hot spots,” as well as overall temperature increases, in the ground shell product. Intense or unduly elevated heat generated in the shells during mechanical milling destroys or degrades nutrients and other desirable components present in the cocoa shells. The localized and general heating in cocoa shells induced by mechanical milling thereof is generally uncontrollable. Also, as indicated, a small portion of the nibs clings to and/or otherwise remains loosely associated with the shell fragment fraction generated by the winnowing operation. The melted fat of this nib portion retained on the shells, together with the shells themselves, may block a conventional mechanical milling system. Therefore, product flavor management for mechanical-milled cocoa shells generally is not feasible. Substantial amounts of cocoa shells are left unmilled and are not re-used, and instead are handled as waste by-product.
Improved and new arrangements are needed for grinding cocoa shells on a commercial scale which reduces heat degradation effects on product and equipment maintenance costs. The invention addresses the above and other needs in an efficient and economically feasible manner.